Dr. Jeff Hersh: Ovarian cancer still difficult to diagnose

Q: My aunt died of ovarian cancer over 10 years ago. Have there been any new techniques developed to screen for this awful disease? Should I be screened?

Dr. Jeff Hersh

Q: My aunt died of ovarian cancer over 10 years ago. Have there been any new techniques developed to screen for this awful disease? Should I be screened?

A: Of the gynecological cancers, cancer of the ovaries kills more American women than any other. It is newly diagnosed in about 25,000 and kills over 15,000 women every year; it is responsible for 5 percent of all female cancer deaths. About 1 in 60 women will develop this disease in their lifetime. Up to 5 percent of women with a first degree relative who had ovarian cancer will develop it.

Ovarian cancer is difficult to diagnose early, primarily because there are often few symptoms in the early stages. When symptoms do develop they are often abdominal symptoms such as pain or bloating, or sometimes urinary symptoms; unfortunately these may be from more advanced disease.

Ovarian cancer has a higher incidence in industrialized nations and in women over 50. Other risk factors include a personal or family history of colon, uterine or breast cancer. Long term hormone replacement therapy (specifically if the hormone treatment was estrogen only) also raises the risk. On the other hand, pregnancy decreases the risk (by about 10 percent for each pregnancy). Breast feeding also lowers the risk.

Like many cancers, ovarian cancer is "staged" to help quantify prognosis and to help guide therapy; the earlier the stage the better the prognosis. The specific treatment depends on the stage of the cancer and other factors specific to each patient. Treatments may include surgery, radiation treatment and/or chemotherapy (either placed directly into the abdomen or used intravenously).

Stage I ovarian cancer is confined to the ovaries. There is a 90 percent five-year survival with this early stage diagnosis.

Stage II cancer has spread from the ovary but is still confined within the pelvis, and the five-year survival rate is about 70 percent.

Stage III cancer has spread throughout the abdomen, and is the stage that symptoms often start to be present. Unfortunately, the five-year survival rate for this later stage is only 15 percent to 20 percent at five years, and this drops even further to 1 percent to 5 percent for stage IV cancer that has spread outside the abdomen.

Since ovarian cancer can be asymptomatic until it is at a more advanced stage, and the prognosis is much worse with advanced stages, it is clearly very important to try and diagnose this cancer as early as possible. However, unlike cervical cancer, where Pap smears have proven to be a very effective screening test, ovarian cancer has been more difficult to screen for.

Pelvic examination, even by very skilled physicians, is very unreliable. Although trans-vaginal ultrasound (US), putting the US probe into the vagina, has proved superior to trans-abdominal US and may detect up to 75 percent of all ovarian cancers, there are significant false positive results (suspicion of ovarian cancer which turns out NOT to be cancer). There has been progress on interpreting the US by using Doppler flow (which can "see" blood flow in the suspected cancer).

There is a blood test that may be used to screen for ovarian cancer, CA-125. Unfortunately, the utility of this test is limited. The higher the level of CA-125, the more likely it is a true predictor of cancer (less likely to be a false positive). However, setting the threshold to call the test "positive" too high may mean missing some cases of ovarian cancer. This means the CA-125 test can have confusing and difficult to interpret results, giving false sense of security in some cases and giving concern in some cases where no cancer exists.

Since the definitive way to determine if a woman has ovarian cancer is to do an exploratory surgery, improving screening methods to minimize unnecessary surgeries has long been a goal.

The results of a recent British study are very welcome news; researchers performed a combination of the CA-125 blood test and US in over 200,000 women to screen for ovarian cancer. This strategy detected 34 of the 38 (almost 90 percent) of the ovarian cancers that developed during the study period, and nearly half were in the earlier stages (stage I or stage II). Although follow up has not been long enough to prove there will be a benefit in survival for this cohort of women, knowing the history of improved prognosis when ovarian cancer is diagnosed in the earlier stages makes improved survival hopeful.

So, consult your gynecologist and discuss your risk factors for ovarian cancer and see what screening is appropriate for you. To learn more, see the National Cancer Institute Web site at www.cancer.gov/cancertopics/types/ov arian/.